Labels with a metallic appearance are often used on products to enhance their consumer appeal. The metallic appearance is normally imparted by a sputtered aluminum coating on the underside of a transparent film. This aluminum or other metal coating, however, can also impart certain undesired properties, e.g., sensitivity to sodium hydroxide, conductivity and/or interference with reception of radio waves or microwaves. For example, a metalized film used as part of a radio frequency identification (RFID) label can render the label unreadable.
One solution to this problem is described in U.S. Pat. No. 6,618,024 in which a metallic effect is imparted to a multi-layer film through the use of multiple nonmetallic reflective surfaces within the film. This film can then be used as part of a RFID label construction without causing interference.
Although the solution of U.S. Pat. No. 6,618,024 is useful, instances exist in which a different method of imparting a nonmetal, metallic appearance is needed. For example, one common form of tamper-evident label leaves behind a patterned adhesive footprint upon removal of the label from the object to which it is attached (e.g., U.S. Pat. Nos. 4,082,873, 4,121,003, 4,184,701 and 5,153,042). Nonmetallic reflective film, such as that described in U.S. Pat. No. 6,618,024, is opaque and as such, it does lend itself for use in a tamper-evident label. Other methods to impart a metallic appearance to a nonmetal label would clearly be useful in a variety of applications.